The most secure way to store your cryptocurrency is to use a hardware wallet, such as the Trezor or Ledger. These devices allow you to store your cryptocurrency with a physical device that cannot be hacked or lost.
You should also use two-factor authentication for any online wallets or exchanges you use to store your cryptocurrency. This means that, in addition to entering your login credentials, you will be required to enter a unique code sent to your phone or email address.
Finally, use secure passwords and keep your computer and wallets updated with the latest security patches.